1. Field of the Invention
The present invention relates to an opto-electronic device for detecting and locating a radiant source.
The locating is made with respect to two reference axes, such as the elevation and azimuthal axes, thus giving the direction of the source with respect to the device. With two devices, it is possible to produce two secant directional locations and thus measure the spatial location of the source.
The term "radiant source" refers either to a distant source or a source which is nearer but is small so that it can be likened to a pinpoint source or to a source at infinity.
2. Description of the Prior Art
There is a known method of making a so-called two-axis deviation measurement of a pinpoint light source or a source than can be likened to a source at infinity by using a four-quadrant detector. The detector is located downline of an optical lens which concentrates the incident radiation received from the source in the form of a parallel beam so as to form, therefrom, a light spot of a defined mean dimension in the photodetection plane. The four respective signals detected are processed by summation and weighting to measure the angular offset in elevation and azimuth with respect to the optical axis of the device. The French patent No. 2.420.144 or the U.S. Pat. No. 4.286.760) describes a device for detecting and locating radiant sources of this type.
With the constantly growing use of lasers in weapon systems (for telemeters, illuminators, etc), it is becoming necessary to warn the crew of a vehicle or aircraft if this vehicle or aircraft becomes illuminated. Corresponding instruments, called laser warning detectors, are aimed solely at detecting the presence of a threat within a wide field around the carrier, for example 360.degree. in azimuth and 90.degree. in elevation.
The above-mentioned locating devices are not usually designed to function in fields of this range. Their adaptation to these fields entails a loss of sensitivity which is incompatible with the detection of the useful signal.
An object of the invention is to overcome the above-mentioned drawbacks by combining the four-quadrant detector with a single upline circular aperture forming a diaphragm.
The fact of having no focusing lens enables a device of this type to have, simultaneously, a wide field which which may be greater than .+-.45.degree., and a large pupil linked solely to the dimension of the detector. The device can further be used in any spectral band and also to receive continuous or pulsed transmissions. It has resolution of a few degrees and its sensitivity, related to the detection surface, is high.